This invention relates to a device for automatically winding a blood pressure measuring cuff around a part of the human body such as an arm, for blood pressure measurement.
In general, for blood pressure measurement, the blood pressure measuring cuff is wound around the upper arm in such a manner that the central part of an air bag made of rubber (hereinafter referred to as "a rubber bag" when applicable) is on the upper arm artery. One or two fingers can be inserted between the rubber bag and the upper arm. In this case, the cuff is set so that the lower edge of the cuff is 2 or 3 cm from the elbow pocket. This is the standard or typical method of winding the cuff around the upper arm for blood pressure measurement.
This method is carried out directly by a doctor or a nurse for accurately measuring blood pressures; that is, the cuff is suitably wound on the upper arm directly by a doctor or a nurse. However, the method is not efficient when trained medical personnel are busy for medical examination, and especially in the case of mass physical examinations.
In order to eliminate this difficulty, a method has been proposed in which a cuff is wound along the inner wall of a cylinder and a person to be examined inserts his upper arm into the cuff thus wound. Air is fed into the rubber bag to inflate the cuff. However, this method is also disadvantageous in the following aspects. If the upper arm of a person to be examined is slender, then it is necessary to increase the quantity of air fed into the rubber bag, and at worst the surface of the upper arm is in circumferential line contact with the cuff surface. In this case, even if the cuff is pressurized to a level higher than the individuals maximum blood pressure, it is impossible to stop the circulation of blood.
Also, in the case of a slender arm, it is necessary to significantly inflate the rubber bag as described above, and therefore the rubber bag must be covered with a slackened fabric. Accordingly, during the process of gradually reducing the pressure to determine the systolic and diastolic blood pressures, the cuff greatly slackened is folded thereby generating noises. Since it is difficult to distinguish the noises thus generated from Korotkov sounds used to determine blood pressure points, this conventional method is liable to cause errors in blood pressure measurement.
In another conventional method, the cuff is wound around a part of the human body by means of an electric motor. However, the method is still disadvantageous in that a person to be examined may be uncomfortable because of the mechanized equipment. Furthermore, another conventional method is known in the art in which the squeezing force of the cuff is adjusted by driving an electric motor under the control of a control device. Such a method was disclosed in U.S. Pat. No. 3,935,984 issued Feb. 3, 1976. This method also involves problems. That is, if the control device is out of order or not satisfactorily functioning, the arm of a person to be examined may be excessively squeezed, with the result that the arm is damaged.